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我正在尝试在我的项目中引入一些并发性。

我现在正在使用并行 gem，并且在并行进程中创建对象时遇到问题。

Parallel.map(["a"], :in_processes => 8) do |i|
  ActiveRecord::Base.connection_pool.with_connection do
    User.create
  end
end

结果是：

/Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:279:in `dump': no _dump_data is defined for class Binding (TypeError)
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:279:in `process_incoming_jobs'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:257:in `block in worker'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:250:in `fork'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:250:in `worker'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:238:in `block in create_workers'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:237:in `each'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:237:in `create_workers'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:201:in `work_in_processes'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:106:in `map'
    from (irb):15:in `irb_binding'
    from /Users/tyler/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/irb/workspace.rb:80:in `eval'
    from /Users/tyler/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/irb/workspace.rb:80:in `evaluate'
    from /Users/tyler/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/irb/context.rb:254:in `evaluate'
    from /Users/tyler/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/irb.rb:159:in `block (2 levels) in eval_input'
    from /Users/tyler/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/irb.rb:273:in `signal_status'
    from /Users/tyler/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/irb.rb:156:in `block in eval_input'
    from /Users/tyler/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/irb/ruby-lex.rb:243:in `block (2 levels) in each_top_level_statement'
    from /Users/tyler/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `loop'
    from /Users/tyler/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `block in each_top_level_statement'
    from /Users/tyler/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `catch'
    from /Users/tyler/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `each_top_level_statement'
    from /Users/tyler/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/irb.rb:155:in `eval_input'
    from /Users/tyler/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/irb.rb:70:in `block in start'
    from /Users/tyler/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/irb.rb:69:in `catch'
    from /Users/tyler/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/irb.rb:69:in `start'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/railties-3.2.13/lib/rails/commands/console.rb:47:in `start'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/railties-3.2.13/lib/rails/commands/console.rb:8:in `start'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/railties-3.2.13/lib/rails/commands.rb:41:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'
Parallel::DeadWorker: Parallel::DeadWorker
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:51:in `rescue in work'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:48:in `work'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:216:in `block (4 levels) in work_in_processes'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:352:in `with_instrumentation'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:215:in `block (3 levels) in work_in_processes'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:210:in `loop'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:210:in `block (2 levels) in work_in_processes'
    from /Users/tyler/.rvm/gems/ruby-1.9.3-p392@arcsite_mysql/gems/parallel-0.8.1/lib/parallel.rb:65:in `block (2 levels) in in_threads'

并行块的任何变化似乎都会导致相同的错误。删除调用create允许程序按预期运行。

4

2 回答 2

0

看起来你返回的东西是不可转储的，所以要么返回 nil 要么使用 Parallel.each 或者 with_connection 实际上并没有返回用户对象，而是一些奇怪的东西......你也可以尝试返回 user.attributes 而不是完整用户目的

于 2013-10-09T14:51:07.183 回答
0

http://ruby.zigzo.com/2012/01/29/the-parallel-gem-and-postgresql-oh-and-rails/

根据上面 Mario 的帖子，PostgreSQL 不允许对多个线程使用相同的连接。我想知道 MySQL 是否相同，另外 MySQL 可能会在访问它时加锁。这是在 PostgreSQL 上并行工作的解决方案：ActiveRecord::Base.connection.reconnect！

于 2015-05-23T21:48:38.897 回答